Altair GraphQL Client vs GraphQL Kotlin

Altair GraphQL Client is an IDE for running and debugging GraphQL queries, mutations and subscriptions. It formats queries, supports file uploads using the multipart specification, and can export query collections. Users can set environment variables for endpoints, headers and queries, then browse schema types and operations in a documentation explorer. Pre-request and post-request scripts and an extensible plugin system add customization options. Altair GraphQL Cloud provides centralized query management, collections, query versioning and shareable query URLs. Official integration packages include Express middleware, Koa middleware, a static build and a Gatsby plugin. The free Basic plan lists up to two team members and 20 queries; Pro costs $7.99 a month per user and lists unlimited team members, teams and queries. The client is available as a web app and on desktop platforms, including Linux, macOS and Windows, with extension and self-hosted options. The maker says the web app is for quick or one-time use, not full development, because it has limitations. Documentation warns that introspection can expose an API schema and that Content Security Policy support is beta.

GraphQL Kotlin is a free Apache License 2.0 collection of libraries, built on graphql-java, for running GraphQL clients and servers in Kotlin. Its schema generator creates schemas from Kotlin code, and a federation module can produce Apollo Federation-compliant schemas. Gradle and Maven plugins generate type-safe Kotlin clients from existing schemas. Generated clients support queries, mutations, batching, coroutines, custom scalars, configurable enum defaults, and Jackson or kotlinx.serialization models. Reference HTTP integrations use Ktor HTTP Client and Spring WebClient, while custom engines are possible. Server implementations target Spring Boot and Ktor; the Spring server uses Spring WebFlux. Ktor supports Kotlin Flow subscriptions over WebSockets with the graphql-transport-ws subprotocol. Its plugin leaves route configuration to the application, allowing selective routes and added authentication logic. The schema generator supports Kotlin Lists, but Sets, arbitrary Maps, and arrays are not supported out of the box. The project is self-hosted, with security guidance in its repository and community support through GitHub Discussions and Kotlin Slack.